Regenerative hot-blast oven



J M HAR'I 'MAN Regenerative Hot-BlesflOven. 221,430

Patented May 11,1880.

Min/awed UNITED STATES PATENT Erica;

JOHN M. HARTMAN, OF PHILADELPHIA, PENNSYLVANIA.

REG ENERATIVE H OT-BLAST OVEN.

SPECIFICATION forming part of Letters Patent No. 227,430, dated May 11, 1880.

Application filed January 23, 1880.

To all whom it may concern:

Be it known that I, JOHN M. HARTMA'N, of Philadelphia, Pennsylvania, have invented a new and useful Improvement in Regenerative Hot-Blast Ovens, of which the following is a specification.

My invention relates to the form and construction of the fire-brick walls within the airtight iron casing.

It consists in placing an enlarged mass of brick-work at the bottom of the combustionchamber to fire the gas; in making the vertical walls of the regenerator of a single width of brick; in staying every alternate wall with cross-bricks which are free to move upon the surface of the abutting wall; in staying the outside wall against the iron shell by bricks which slide into the wall and prevent the bursting of the iron shell.

In the drawings making part of this specification, Figure l is a plan of the top of the fire-brick in the regenerator. Fig. 2 shows the bottom of the fire-brick work in an inverted position. Fig. 3 is a vertical section through the regenerator on line X Y.

A regenerative hotblast oven for heating the blast for blast-furnaces consists of a mass of brick-work with passages through it, the whole inclosed in a circular air-tight iron case, A. A pipe and valve for the admission of gas are shown at B. Air -pipes I) serve the purpose of burners. The inlet for cold air to be heated is shown at O, and the outlet for the heated blast is shown at D. Relief dust-valves E are also shown, one being on each side of the stove at the bottom. On one side of the stove is the combustion-chamber G, and the remainder of the stove is occupied with a mass of brick -work having large surfaces, for receiving, storing, and giving out heat. This is the regenerator.

In the usual workingof the stove, gas is burned for four hours in the combustion-chamber, and the heat generated is absorbed by the regenerator and stored up for use. The gas is then turned off and the blast is blown through the inlet 0 and passes from the stove by outlet-valve D in a highly-heated state. This continues for about two hours, when the regenerator becomes exhausted of heat, the

blast is shut off, and gas again turned on, as before.

The period of burning gas is called stove on gas. The period of blast passing through the stove is called stove on a blow. The changing from stove on a blow to stove on gas is sometimes attended by explosions, tearing the brick-work and dangerous to the stove, owing to the combustion chamber being too cold to ignite the gas. This I prevent by building a thick mass of inclined brick-work, H, at the bottom of the combustion-chamber,

considerably below the blast-outlet D, so that- -it is but little cooled by the current of the blast while the stove is on a blow, and it remains red-hot, ready to ignite the gas as soon as it is admitted, thereby insuring an immediate and perfect combustion of the gas.

To distribute the gas evenly through the ie- I generator I use a D-shaped combustion-chamber, which causes the gas as it passes over the straight part of the top edge of the chamber to spread itself evenly over the entire top of the regenerator. The outlet-valve D, however, being opposite the center of the regenerator, the tendency of the gas is to pass down the open center of the regenerator by the shortest out, leaving the sides comparatively free from gas. I obviate this by buildingthe central wall, K, at right angles to the straight wall L of the combustion-chamber. This distributes the currents equally and avoids a central passage.

The vertical walls P R of the regenerator have heretofore been built of nine-inch firebrick. These are nine inches long. two and a half inches thick, and four and a half inches wide, and are laid side by side, forming a wall nine inches thick, and about every fifth course is laid with headers, to bind the wall and make it stable. Owing to the extremely slow conducting power of fire-brick, the heat which is buried in a nine-inch wall cannot be extracted in the two hours the stove is on a blow, and is consequently useless. I make my walls of this aforementioned brick set on their flat sides and lengthwise of the wall, forming a four and a half inch wall, and thus make a far more eflicient regenerator than is now placed within the iron shell.

All the walls of a regenerator as now built are not always at the same temperature, and consequently the varying expansion of the brickwork cracks and disarranges the structure when built, as heretofore, with longitudinal and cross walls bonded together solid.

To prevent these thin walls as constructed by me from buckling, and to retain them vertically, projecting bricks m are built into every alternate wall P, which extend sidewise each way and only just touch the next Wall on each side. These projecting bricks m are placed at certain intervals apart both horizontally and vertically, and thereby permit the adjacent walls to expand and contract without tearing each other.

The walls P are notched into the central wall, K, thereby giving freedom for the brickwork of the regenerator to accommodate itself to the varying temperature.

After the stove has finished a blow it is full of blast under pressure, which must be released before gas will enter the stove. To relieve this pressure, quick-acting relief-valves E are applied at the bottom of the stove, one on each side, which, on being suddenly opened, cause the escaping blast to carry off the dust deposited on the bottom of the stove. This prevents the need of frequent cleaning, as heretofore required.

To prevent the iron shell being ruptured by the expansion of the brick-work, Ileave a space, a, between the shell and the brick-work, and project one or more courses of brick-work, S, Behind this projecting against the shell.

course of brick a space, W, is left, into which the projecting bricks are pushed when the expansion takes place, thus preventing a rupture of the shell.

I claim- I 1. In a regenerative hot-blast oven, the combination of the combustion-chamber Gr, the enlarged mass of brick-work H, for firing the gas opposite the gas-inlet B, and the outlet D above, for the exit of the heated air free from contact with the firing mass, as herein described.

2. In aregenerative hot-blast oven, the combination of the straight wall L of the combustion-chamber with the central dividing-wall, K, of the regenerator, which is notched into and slides against the said wall L, as and for the purpose described.

3. In a regenerative hot-blast oven, the vertical walls PR, stayed. by cross-bricks m, which slide against the surface of the contiguous walls and permit their free expansion, as herein described.

4. In aregenerative hot-blast oven, the combination of the shell A, the interior brick-work, separated therefrom by a space for expansion, and the sliding bricks S, placed in recesses in the brick-work which are deeper than the brick, thus leaving a cavity behind the brick, as and for the purpose described.

' JOHN M. HARTMAN Witnesses:

EDWD. BROWN, JOHN F. GRANT. 

